A number of studies have shown that added sugars are bad for your health. One study found that compared to those who got 8% of calories from added sugar, those who got 17% to 21% of calories from added sugar had a 38% increased risk of cardiovascular disease mortality. The risk of cardiovascular disease for those who obtained 21% or more calories from added sugar was 103% greater!
The two most common types of added sugar by far are high fructose corn syrup (a sweetener processed from corn starch) and sucrose (table sugar). Is all added sugar bad, or is one worse than the other?
High Fructose Corn Syrup vs. Sugar
A new study fed mice a diet either composed of 25% high fructose corn syrup or 25% table sugar for 40 weeks. Afterwards, the mice were released into a space where they competed for territory, resources and mates. The researchers found that female mice that were fed the high fructose corn syrup diet had a 1.9x higher mortality rate. They also produced 26.4% fewer offspring. There was no observable effect on male mice.
So, high fructose corn syrup appears to be worse for female mice, but what about humans?
Another study followed 353,751 people for up to 13 years and tracked their total sugars, added sugars, total fructose, added fructose, total sucrose, and added sucrose consumption. The researchers found that all-cause mortality was associated with total sugar, total fructose and added fructose in women and total fructose in men. These sugars were found to be harmful when obtained from beverages, but sugar was actually somewhat protective when obtained from solid food (perhaps because of the other nutrients that were consumed alongside the sugar).
All sugar doesn’t appear to be created equal. While there still needs to be more research on the topic, there are also metabolic reasons to be wary of fructose. According to Harvard,
Virtually every cell in the body can use glucose for energy. In contrast, only liver cells break down fructose. What happens to fructose inside liver cells is complicated. One of the end products is triglyceride, a form of fat. Uric acid and free radicals are also formed.
None of this is good. Triglycerides can build up in liver cells and damage liver function. Triglycerides released into the bloodstream can contribute to the growth of fat-filled plaque inside artery walls. Free radicals (also called reactive oxygen species) can damage cell structures, enzymes, and even genes. Uric acid can turn off production of nitric oxide, a substance that helps protect artery walls from damage. Another effect of high fructose intake is insulin resistance, a precursor to diabetes.
So, fructose may be the real villain. Sucrose is 50% glucose and 50% fructose. High fructose corn syrup is 45% glucose and 55% glucose. So, both should be limited. However, high fructose corn syrup appears to be somewhat worse for your health.
Ruff, James S., et al. “Compared to sucrose, previous consumption of fructose and glucose monosaccharides reduces survival and fitness of female mice.” The Journal of nutrition 145.3 (2015): 434-441.
Tasevska, Natasha, et al. “Sugars and risk of mortality in the NIH-AARP Diet and Health Study.” The American journal of clinical nutrition (2014): ajcn-069369.
Yang, Quanhe, et al. “Added sugar intake and cardiovascular diseases mortality among US adults.” JAMA internal medicine 174.4 (2014): 516-524.